code: def forward_cpu(self, inputs):
      return self._forward(inputs)
  
file_path: chainer/chainer/functions/array/spatial_transformer_grid.py
imports: import numpy
  import chainer
  from chainer import backend
  from chainer.backends import cuda
  from chainer import function
  from chainer.utils import argument
  from chainer.utils import type_check
label_desc: Use image node_id 3 for calling the SpatialTransformerGrid obj's underlying member method code with example usage: obj.forward_cpu(inputs) and returns: self